Hand-loading cartridges (also called reloading) is a manual process of loading and assembling firearm cartridges or shotgun shells from individual components including, for example, a case (or hull), primer, powder, and bullet (or shot).
The accuracy of a rifle shot, or other small-arms intentional discharge, significantly increases when the shooter uses a hand-loaded cartridge compared to a bulk, “off-the-shelf” premade cartridge. This improved accuracy, in part, is a result of less variability in weight and balance obtained by precise hand loading of the cartridges. Commercially purchased, pre-assembled, bulk quantities of cartridges, often have a higher variability in weight and balance, which contributes to inaccuracies and variability shot to shot.
Hobbyists, professionals, and recreational shooters often elect to hand-load cartridges—not only for the enjoyment of the task—but also to reduce or eliminate variables that prevent repeatable performance. Further, the hand loading of cartridges enables the shooter to customize the round for the task at hand, whether it is competitive shooting events, hunting, or target practice. Accordingly, customized rounds may be constructed to optimize specific performance parameters such as bullet velocity, accuracy between firings, and shot-to-shot consistency.
The hand-loading process can realize increased accuracy and precision through improved consistency of manufacture, by selecting the optimal bullet weight and design, and by tailoring bullet velocity to the purpose. Each reloaded cartridge can have each component carefully matched to the rest of the cartridges in the batch. Brass cases can be matched by volume, weight, and concentricity, bullets by weight and design, powder charges by weight, type, case filling (amount of total usable case capacity filled by charge), and packing scheme (characteristics of granule packing).
In addition to these critical items, the equipment used to assemble the cartridge also has an effect on its uniformity/consistency and optimal shape/size. Normally, a reloading die is used to size the cartridges to more precisely match the cartridge to the exact size of the chamber in a given firearm. Typical reloading die kits are available, for example, from Sinclair International (www.sinclairintl.com) and are manufactured by Lee Precision, Inc. such as model number 100-010-122WS for hand guns or a Redding (manufacturer) Type-S model number 749-007-898 WS die set for rifles.
Guns and reloading dies have been made for over a century; however there has never been a reliable, accurate way to adjust a loading die for a specific rifle/pistol chamber. In part, the difficulty in adjusting a loading die for a specific chamber is due to inherent variation in the tolerances maintained during the manufacturing of the various components and tools. Modern manufacturing processes will yield highly predictable results in the tolerances of the parts they produce, but a natural, statistical distribution of sizes remains part of the controlled process. This natural variation, when compounded for each component used in assembly of a round, plus the natural, accepted variation in the tools used to measure the components and the natural variation inherent in the firing components, results in a stacked variation that is manifested as shot inconsistency.
To counter this shot inconsistency, some shooters will try a rudimentary sorting of the components in an attempt to size the round to the chamber. This may reduce the shot-to-shot variation experienced by the variation in tolerances that are inherent in the manufacturing of chambers, reloading dies, shell holders and loading presses, all of which contribute to the difficulty and inaccuracy of improper die adjustment. However, there is not a systemic, proven, repeatable method or system or tool that enables a shooter to consistently improve the selection of components and reloading process. Thus, much of the current hand reloading process is based solely on an artful combination of long-practiced, experience-based skill and some guesswork.
Further, hand reloading is not without inherent danger. For a given firearm, improperly adjusted dies can be dangerous. For example, if the shoulder of the cartridge is pushed back, this creates excessive headspace in the firearm, which can result in a case head separation, causing the firearm to explode when pressures from the cartridge escape. Likewise, if the die is not adjusted properly and the shoulder of the cartridge is not pushed back sufficiently, the cartridge will not chamber in the firearm.
Obtaining the proper results of hand-loaded ammunition—thus far—is only achieved thru trial-and-error attempts by the hand-loader. In the current art to achieve the desired setting a cartridge needs to be fired and reloaded several times until the action of the bolt becomes hard to close. The hand loader then attempts to screw the die down progressively until the shoulder of the cartridge is compressed and sized enough to allow chambering. Acceptable tolerances in chamber dimensions usually run or vary from about 0.000 to 0.006-inches. If the cartridge is re-sized repeatedly with a 0.006-inch headspace, head separation is inevitable after repeated firings.
Reloading dies also have tolerances and the usual reference is to screw the die down against the shell holder (which also has tolerances) hoping to size the cartridge sufficiently to chamber, yet not be sized to the point of being dangerous by tolerance variations in dies and shell holders.
Reloading dies are generally sold in sets of two or three dies, depending on the shape of the case. The first die typically is used to size and de-cap, and expand the neck. The last die in the set seats the bullet and may apply a crimp. Special crimping dies are often used to apply a stronger crimp after the bullet is seated.
Reloading dies work in conjunction with a press. Once the appropriate die is selected and loaded with a cartridge case, they are positioned under a ram of a die that then forces the case to conform to the wall of the die, or—depending on the operation—crimp the case, or seat a primer.
Seating the primer is another important step in hand loading a cartridge. Again, the hand loading operation is attempting to create a very tight, repeatable, and exact tolerance match between the finished cartridge and the firing chamber of a given firearm. However, because of the complicated stack up of tolerances, which are unique to each hand-loader's set up, for over a century primers have been seated by feel. This is a highly variable, highly subjective, and skill-intensive manual operation and no two people have the same feel. This subjective feel results in crushed and irregular seated primers, which in turn result in misfires and poor ignition qualities. Currently, all hand-held and bench mounted priming tools are used by this subjective “feel technique.”
This highly variable feel technique to self-loading ammunition is counter-productive for recreational and competitive shooters. To improve target consistency shooters desire a reduction in variables that affect their shots. Although little can be done for ambient lighting, wind, and weather (outdoors), one variable in control of the shooter is attaining a repeatable and consistent muzzle velocity. Once factor contributing to muzzle velocity is proper seating of the primer.
Achieving a low standard deviation in muzzle velocities is the key to long range shooting success and victory over other competitors. Eliminating the vertical stringing in group size by achieving single digit velocities (low standard deviations in velocity) is most important to long range shooters, which are greatly impacted by the duration of the flight and gravity action on the shot due to the extreme ranges involved.
Primer seating and depth of the primer seated contribute to consistent ignition, which in-turn relates to low deviations in velocity. As primer pockets expand, the feel one is expected to know, changes, and this results in inconsistent seating depth, which affects velocity and ignition. The depth at which the primer seats has a significant impact on the behavior of the ammunition both during firing and after it leaves the muzzle. For example, firing pin protrusion and inertia energy ignite the primer in the cartridge case, thus when the primer is seated to irregular depths, protrusion and ignition are affected and this results in inconsistent ignition, misfires and extreme spreads in velocities from projectile to projectile during a shooting session.
When primers are seated consistently to an exact depth, the consistency of the spark produced by the primer, which ignites the powder column, is improved. Spark ignition, spark intensity, and cone of spark fire all contribute to uniform burn rates and low standard deviations in muzzle velocity.
When primers are seated to the bottom of the primer pocket in the cartridge case, the pressure developed from burning powder pushes the primer back against the bolt-face; this—in turn—interrupts the harmonic node traveling down the barrel. And, this results in inconsistent timing and exit of the bullet from the barrel and affects accuracy. Minimizing and or eliminating “primer back-up” by properly seating the primer is therefore of paramount importance as it negates harmonic interruption.
English, in U.S. Pat. No. 3,049,044 issued on 1962 Aug. 14, teaches one representative example of known devices and methods for seating primers in a cartridge. Lee, in U.S. Pat. No. 4,222,305 issued on 1980 Sep. 16, teaches another hand tool for installing (seating) primers in ammunition cartridges. Both of these aforementioned teaching in the art rely on the feel technique for setting the desired primer position relative to the bottom of the shell or casing and further rely solely on a threaded member for infinite adjustability of this seating position. Yet another hand-held tool for seating a primer includes the disclosure of Brand et el. in U.S. Pat. No. 6,260,463 issued 2001 Jul. 17.
Markle, in U.S. Pat. No. 5,025,706 issued 1991 Jun. 25, teaches a bench-mounted, controlled-depth primer-seating tool that includes a dial measurement component.
Despite the known teachings in the art, there is yet still a need for a device and system that ensures proper primer seating and consistent, repeatable primer seating for the hand loading of ammunition.